The LoadDistributorTargetSelector attempts to do the same job as the
FailoverTargetSelector, but to choose an alternate target on every request
rather than just when a fault occurs.
The LoadDistributorTargetSelector uses the same FailoverStrategy interface as
the FailoverTargetSelector, but has a few significant limitations:
1. Because the LoadDistributorTargetSelector needs to maintain a list of targets
between calls it has to obtain that list without reference to a Message.
Most FailoverStrategy classes can support this for addresses, but it cannot
be supported for endpoints.
If the list of targets cannot be obtained without reference to a Message then
the list will still be obtained but it will be specific to the Message and thus
discarded after this message has been processed. As a consequence, if the
strategy chosen is a simple sequential one the first item in the list will
be chosen every time.
Conclusion: Be aware that if you are working with targets that are
dependent on the Message the process will be less efficient and that the
SequentialStrategy will not distribute the load at all.
2. The AbstractStaticFailoverStrategy base class excludes the 'default' endpoint
from the list of alternate endpoints.
If alternate endpoints (as opposed to alternate addresses) are to be used
you should probably ensure that your FailoverStrategy overrides getAlternateEndpoints
and calls getEndpoints with acceptCandidatesWithSameAddress = true.
a failover endpoint if one is available
Note: The only difference between this and the super implementation is
that the current (failed) address is removed from the list set of alternates,
it could be argued that that change should be in the super implementation
but I'm not sure of the impact.